The study of the evolution in the diagnosis and treatment of autism is a lesson in the dangers of medical beliefs or doctrines that are not grounded in medical science. The early descriptions of autism suggested that it was the result of childhood psychoses or psychodynamic disturbances of parent-child relationships. This flawed conceptualization of autism spectrum disorders (ASD) gave way to advances in medical science, which have established ASD as a neurobiological disorder of early brain development. There are many genetic, epigenetic, metabolic, hormonal, immunological, neuroanatomical and neurophysiological etiologies of ASD, as well as an array of gastrointestinal and other systemic co-morbid disorders. Thus, ASD are a biologically heterogeneous population with extensive neurodiversity. Early identification and understanding of ASD is crucial; interventions at younger ages are associated with improved outcomes. The advent of understanding the biological sub-phenotypes of ASD, along with targeted medical therapies, coupled with a multimodal therapeutic approach that encompasses behavioral, educational, social, speech, occupational, creative arts, and other forms of therapies has created a new and exciting era for individuals with ASD and their families: "personalized" and "precision" medical care based upon underlying biological sub-phenotypes and clinical profiles. For many individuals and their families dealing with the scourge of autism, their long and frustrating diagnostic journey is beginning to come to an end, with a hope for improved outcomes and quality of life.
Keywords: Autism Spectrum Disorder; History; Leo Kanner; Personalized Medicine; Phenotype; Precision Medicine.